Cache Refreshing Scenarios Cache Configuration Tuning

10-2 Oracle Fusion Middleware Performance and Tuning Guide Note that Oracle Web Cache is limited by the available addressable memory. Additional memory can increase performance and scalability. For information about the amount of memory needed, see Section 10.2.2, Memory Configuration . Oracle Web Cache has two processes: one for the administration server and one for the cache server. ■ The administration server process is used for configuring and monitoring Oracle Web Cache. This process consumes very little CPU time. However, when viewing the statistics pages in Oracle Web Cache Manager, the administration server process must query the cache server process to obtain the relevant metrics. Accessing the statistics pages frequently, or setting a high refresh rate on a statistics page can affect cache server performance. ■ The cache server process uses three threads: one to manage the front-end activities, a second to manage the back-end activities, and a third to process requests. For a cost-effective way to use Oracle Web Cache, run it on a fast two-CPU dedicated computer with lots of memory. See the Oracle Fusion Middleware Administrators Guide for Oracle Web Cache for information about various deployment scenarios. For a Web site with more than one Oracle Web Cache instance, consider installing each instance on a separate two-CPU node, either as part of a cache cluster or as a standalone instance. When Oracle Web Cache instances are on separate nodes, you are less likely to encounter operating system limitations, particularly in network throughput. For example, two caches on two separate two-CPU nodes are less likely to encounter operating system limitations than two caches on one four-CPU node. Of course, if other resources are competing with Oracle Web Cache for CPU usage, you should take the requirements of those resources into account when determining the number of CPUs needed. Although a separate node for Oracle Web Cache is optimal, you can also derive a significant performance benefit from Oracle Web Cache running on the same node as the rest of the application Web server.

10.2.2 Memory Configuration

To avoid swapping documents in and out of the cache, configure enough memory for the cache. Generally, the amount of memory maximum cache size for Oracle Web Cache should be set to at least 512 MB. Your applications memory requirements can vary based upon factors such document size, number of documents, the number of HTTP headers returned, and whether ESI is present. To get a close approximation on the maximum amount of memory required, you may apply the formula provided below. If your application uses ESI then all templates and document fragments must be accounted for when figuring the TotalDocs and the AvgDocSize. Estimated Cache size in bytes = 1.25 TotalDocs AvgDocSize8192+1 8192+ 16384 ■ 0.25 accounts for the run time memory usage. The Web Cache action limit is set to 5 below than the maximum Web Cache size by default. Web Cache also allocates 5 of the total cache size to optimize access misses that cannot be cached. ■ TotalDocs refers to the total number of documents you intend to place in Web Cache. ■ The AvgDocSize is self-explained. ■ Remember to convert the estimated cache size is returned in bytes by the formula.